A first category of replaceable blades for agricultural use such as disc blades, coulter blades and planter blades often have a circular sharpened outer periphery. These blades that are typically rotatably mounted on a shaft and they rotate about the shaft due to contact with the soil as the implement moves over the top of the ground. U.S. Pat. No. 5,167,286 to Bossier shows gangs of discs of this type. Because of the circular shape, there is slippage between the blade and the ground as the blade is towed through a field, meaning essentially that the rotation of the blade is not constant even when the frame to which the shaft is attached is moving constantly in a forward direction. This slippage causes the blades to not cut the trash in a consistent manner. As the blade slips, trash will build up in front of the blade before the blade goes over the trash to cut it. This results in incomplete and inconsistent cutting of the trash.
A second category of replaceable blades of the aforementioned type have notches, flutes or waves which cause the blade to constantly rotate without slipping as the implement to which they are attached moves forwardly over the surface of the ground. Cutting surfaces on the outer periphery of notched blades are usually not sharp inside the notches, but only on the original circular portion of these blades before the notches have been cut out from them. In those blades, such as those shown in U.S. Pat. No. 6,554,079 to Bruce, trash is trapped in the notches but the notched portions do not always cleanly cut the trash though the notched portions of the blades may tear the trash into pieces to some extent.
Even if the notched portions of the notched blades were to be sharpened, for example as shown in U.S. Pat. No. 2,369,051 to Cahoy, an irregular pattern in the cutting edge results in inconsistent cutting of the trash.
Fluted and wavy coulters or discs, for example as shown in U.S. Pat. No. 5,649,602 to Bruce, has an outer peripheral cutting surface that is formed on the blade when it is circular and then the waves are formed into the blade during a hot forming step, making the cutting surfaces still close to being formed along a circular path that is moves from one side and then to the other side from a plane perpendicular to the axis of rotation of the blade. So there is very little trapping of trash between one wave of the outer periphery and the next adjacent one as the blade rotates and passes through the soil. This is in contrast to the aforementioned notched blades that trap trash in the notches as the blade rotates through the soil.
U.S. Pat. No. 5,495,897 to Javerlhac has a clover leaf like design that is mounted on a shaft. A disc set 31 is seen in FIG.8 of Javerlhac is mounted fixed to a shaft for rotation with the shaft. The blades do not rotate on the shaft independently of each other. The Javerlhac blades are out of phase so Javerlhac's device will work like a plow in that the lobes of one disk throw dirt to the next adjacent one sequentially. The blades 5 of U.S. Pat. No. 2,369,051 to Cahoy similarly rotate with the shaft on which they are mounted and do not rotate on the shaft independently with other blades that are disposed for rotation independently on the same shaft. Consequently blades like those of Javerlhac and Cahoy that are designed to rotate with the shaft with other similar blades out of phase rotating on the same shaft fall into a third category of blades.
Planter blades are used on a planter or drill for cutting a slot in the ground and are also used to open a furrow so that seeds may be dropped in the furrow before the seeds are then covered up by closing the furrow and packing down the soil over the seeds. These planter blades, for example as shown in U.S. Patent No. 6,752,095 to Rylander et al., are typically just a round flat steel disc with a sharpened outer peripheral edge, but it is extremely important that each planter blade penetrate the ground and cut trash if trash is in the path of the planter blade. It is critical that trash not build up in front of a planter blade, which is prone to happen when that blade has a typical prior art type circular outer periphery cutting surface on it. All of the aforementioned patents are hereby incorporated herein by reference in their entirety.
Accordingly, there is a need for a disc, coulter or planter blade that cuts trash and penetrates the soil better than those available in the past.